Think this is my first post here, but I thought like to say I've tried adding the repo at http://qt-kde.debian.net to get KDE4.5 and found that sometimes dolphin would freeze for a couple of minutes (though not actually crash), so I've now reinstalled aptosid apate without that repo. For what it's worth have been able to get a newer Iceweasel, not by adding a repository but with individual packages and I've not had any problems. I can't actually remember where I got them but they're called: